Transcription analysis of Ganoderma lucidum reveals candidate genes and pathways in response to excess exogenous indoleacetic acid (IAA)

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Abstract

Known as auxin which regulate the plant growth, indoleacetic acid (IAA) was also found to be synthesized in basidiomycetes Ganoderma lucidum in our previously work. In the present study, the effect of excess exogenous IAA on mycelium of G. lucidum was determined. Result shows that the mycelium growth was significantly inhibited under 10 μM IAA treatment. The transcripts of both the IAA treated group and the control group were measured by high-throughput RNAseq and a total of 1605 differentially expressed genes (DEGs) were obtained. All the DEGs were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. “Oxidoreductase activity”, “electron transport”, “catalytic activity”, “cellular aromatic compound metabolic process” were listed as the most remarkable enrichment GO terms. The deep investigation of DEGs reveals that aldh gene which participate in the IAA biosynthesis was down-regulated whereas two IAA efflux carrier were up-regulated. KEGG pathway analysis shows that the DEGs were significantly enriched in steroid biosynthesis pathway, in which 12 genes participated in ergosterol biosynthesis were up-regulated. Excess IAA may also bring oxidative stress as the expression level of antioxidative enzymes were affected. This work provides a framework for studying the mechanisms of auxin in G. lucidum.